KR20080013231A - Plasma display apparatus - Google Patents

Abstract

A plasma display device is provided to decrease an afterimage according to a variation in an APL(Average Power Level) adaptively by adjusting the number of sustain signals per unit grayness. A plasma display device includes a PDP(Plasma Display Panel)(100) and a driver(110). The PDP includes first and second electrodes. During a sustain period, the driver supplies a sustain signal to at least one of the first and second electrodes. During a specific mode, the driver decreases the number of sustain signals per unit grayness which is supplied to at least one of the first and second electrodes. The driver changes a decrease number of the sustain signals according to the APL(Average Power Level) at first and second levels.

Description

Plasma Display Apparatus {Plasma Display Apparatus}

1 is a view for explaining the configuration of a plasma display device according to an embodiment of the present invention.

2A to 2B are views for explaining an example of a plasma display panel that can be included in a plasma display device according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining a frame for implementing gradation of an image in a plasma display device according to an embodiment of the present invention; FIG.

4 is a view for explaining an example of the operation of the plasma display device according to an embodiment of the present invention.

5A to 5B are diagrams for explaining another form of the rising ramp signal or the second falling ramp signal.

Fig. 6 is a diagram for explaining another type of the sustain signal.

7 is a diagram for explaining a specific mode.

FIG. 8 is a diagram for explaining a reason for reducing the number of sustain signals per unit gray scale in a specific mode. FIG.

9 is a diagram for explaining an average power level.

FIG. 10 is a diagram for explaining an example of a method of reducing the number of sustain signals per unit gray level in relation to an average power level. FIG.

FIG. 11 is a diagram for explaining another example of a method of reducing the number of sustain signals per unit gray level in relation to an average power level. FIG.

<Description of the numbers for the main parts of the drawings>

100: plasma display panel 110: driver

The present invention relates to a plasma display device (Plasma Display Apparatus).

The plasma display apparatus includes a plasma display panel having electrodes formed thereon, and a driving unit supplying predetermined driving signals to the electrodes of the plasma display panel.

In general, a phosphor layer is formed in a discharge cell (Cell) partitioned by a partition, and a plurality of electrodes are formed in the plasma display panel.

The driver supplies a driving signal to the discharge cell through the electrode.

Then, the discharge is generated by the drive signal supplied in the discharge cell. Here, when discharged by a drive signal in the discharge cell, the discharge gas filled in the discharge cell generates vacuum ultraviolet rays, and the vacuum ultraviolet light emits the phosphor formed in the discharge cell to emit visible light. Generate. The visible light displays an image on the screen of the plasma display panel.

On the other hand, in the conventional plasma display device, a problem occurs that an afterimage occurs when an image is implemented on a screen.

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a plasma display apparatus which reduces the occurrence of afterimages by improving a method of reducing the number of sustain signals per unit gray level in relation to an average power level in a specific mode. There is this.

The plasma display device of the present invention for achieving the above object is a plasma display panel including a first electrode and a second electrode parallel to each other, and at least one of the first electrode or the second electrode in the sustain period for displaying the image; Supply a signal, and reduce the number of sustain signals per unit gray scale supplied to at least one of the first electrode and the second electrode in a specific mode, and the average power level is determined by the first level. And a driving unit which makes the number of decreases of the sustain signal per unit gray level different from the number of decreases of the sustain signal per unit gray level at a second level different from the first level.

Further, the first level is lower than the second level, and the number of decreases of the sustain signal per unit gray level at the first level is greater than the number of decreases of the sustain signal per unit gray level at the second level.

The specific mode may be a mode in which an image having substantially the same average power level is displayed for a threshold time or more.

The threshold time may be determined within a range of 30 seconds or more and 10 minutes or less.

Hereinafter, a plasma display device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining the configuration of a plasma display device according to an embodiment of the present invention.

1, a plasma display apparatus according to an embodiment of the present invention includes a plasma display panel 100 and a driver 110.

The driver 110 supplies a sustain signal to at least one of the first electrode and the second electrode of the plasma display panel 100 in the sustain period for displaying an image, and in the specific mode, the first electrode or the second electrode. The number of sustain signals per gray level supplied to at least one of the plurality of gray levels is reduced, and the number of decreases of the sustain signals per gray level at an average power level is different from the first level and gray levels at a second level. It is different from the number of decreases in the sugar sustain signal.

Here, in FIG. 1, only the case in which the driving unit 110 is formed in one board form is illustrated, but in the present invention, the driving unit 110 is divided into a plurality of board forms according to electrodes formed on the plasma display panel 100. It is also possible to lose.

For example, when a first electrode and a second electrode parallel to each other, and a third electrode crossing the first electrode and the second electrode are formed in the plasma display panel 100 included in the plasma display device of the present invention. The driving unit 110 may include a first driving unit (not shown) for driving the first electrode, a second driving unit (not shown) for driving the second electrode, and a third driving unit (not shown) for driving the third electrode. It can be divided.

The driving unit 110 of the plasma display device of the present invention will be more clearly described later.

Here, the plasma display panel 100 includes an electrode, which will be described in detail with reference to FIGS. 2A to 2B attached to an example of the plasma display panel 100.

2A to 2B are views for explaining an example of a plasma display panel that may be included in a plasma display device according to an embodiment of the present invention.

First, referring to FIG. 2A, the plasma display panel according to the present invention includes a front substrate 201 in which first electrodes 202 and Y and second electrodes 203 and Z are parallel to each other, and the above-described first electrode ( The rear substrate 211 on which the third electrodes 213 and X intersecting the 202 and the Y and the second electrodes 203 and Z may be formed may be bonded to each other.

Here, the electrodes formed on the front substrate 201, preferably the first electrodes 202 and Y and the second electrodes 203 and Z, generate a discharge in a discharge space, that is, a discharge cell, and discharge the same. The discharge of the cell can be maintained.

The dielectric layer covers the first electrode 202 and the second electrode 203 and Z on the front substrate 201 where the first electrode 202 and the second electrode 203 and Z are formed. Preferably, the upper dielectric layer 204 can be formed.

This upper dielectric layer 204 limits the discharge current of the first electrode 202, Y and the second electrode 203, Z and between the first electrode 202, Y and the second electrode 203, Z. Can be insulated.

A protective layer 205 is formed on the top surface of the upper dielectric layer 204 to facilitate discharge conditions. The protective layer 205 may be formed through a method of depositing a material such as magnesium oxide (MgO) on the upper dielectric layer 204.

On the other hand, the electrode, preferably the third electrode (213, X) is formed on the back substrate 211, the third electrode 213, is formed on the upper side of the back substrate 211, the third electrode (213, X) is formed A dielectric layer, preferably lower dielectric layer 215 may be formed to cover X).

The lower dielectric layer 215 may insulate the third electrodes 213 and X.

On top of the lower dielectric layer 215, a partition 212, such as a stripe type, a well type, a delta type, a honeycomb type, for partitioning a discharge cell, that is, a discharge cell, is formed. Can be formed. Accordingly, discharge cells such as red (R), green (G), and blue (B) may be formed between the front substrate 201 and the rear substrate 211.

In addition to the red (R), green (G), and blue (B) discharge cells, it is also possible to further form a white (W) or yellow (Yellow: Y) discharge cell.

On the other hand, the pitch of the red (R), green (G) and blue (B) discharge cells in the plasma display panel included in the plasma display device according to an embodiment of the present invention may be substantially the same. However, the pitches of the red (R), green (G) and blue (B) discharge cells may be different in order to match the color temperature in the red (R), green (G) and blue (B) discharge cells.

In this case, the pitch may be different for each of the red (R), green (G), and blue (B) discharge cells, but the pitch of one or more discharge cells among the red (R), green (G), and blue (B) discharge cells. May be different from the pitch of other discharge cells. For example, the pitch of the red (R) discharge cells is the smallest, and the pitch of the green (G) and blue (B) discharge cells may be larger than the pitch of the red (R) discharge cells.

Here, the pitch of the green (G) discharge cells may be substantially the same as or different from the pitch of the blue (B) discharge cells.

In addition, the plasma display panel included in the plasma display apparatus according to the exemplary embodiment of the present invention may have not only the structure of the partition wall 212 illustrated in FIG. 2A but also the structure of the partition wall having various shapes. For example, the partition 212 includes a first partition 212b and a second partition 212a, where the height of the first partition 212b and the height of the second partition 212a are different from each other. At least one of the first barrier rib 212b and the second barrier rib 212a, and a channel type barrier rib structure having a channel usable as an exhaust passage, at least one of the first barrier rib 212b and the second barrier rib 212a. Grooved partition wall structure having a groove formed in the groove will be possible.

Here, in the case of the differential partition structure, it is preferable that the height of the first partition 212b of the first partition 212b or the second partition 212a is lower than the height of the second partition 212a. In addition, in the case of the channel type barrier rib structure or the groove type barrier rib structure, it is preferable that the channel is formed in the first barrier rib 212b or the groove is formed.

On the other hand, in the plasma display panel according to an embodiment of the present invention, although the red (R), green (G), and blue (B) discharge cells are shown and described as being arranged on the same line, they may be arranged in different shapes. It will be possible. For example, a delta type arrangement in which red (R), green (G) and blue (B) discharge cells are arranged in a triangular shape may be possible. In addition, the shape of the discharge cell may also be a variety of polygonal shapes, such as pentagonal, hexagonal, as well as rectangular.

Here, it is preferable that a predetermined discharge gas is filled in the discharge cells partitioned by the partition walls 212.

In addition, a phosphor layer 214 that emits visible light for image display may be formed in the discharge cells partitioned by the partition wall 212. For example, red (R), green (G), and blue (B) phosphor layers may be formed.

In addition to the red (R), green (G), and blue (B) phosphors, it is also possible to further form a white (W) and / or yellow (Y) phosphor layer.

In addition, the phosphor layers 214 of the red (R), green (G), and blue (B) discharge cells may have substantially the same thickness or may differ from one or more. For example, if the thickness of the phosphor layer 214 in at least one of the red (R), green (G), and blue (B) discharge cells is different from the other discharge cells, green (G) or blue (B) The thickness of the phosphor layer 214 in the discharge cell may be thicker than the thickness of the phosphor layer 214 in the red (R) discharge cell. Here, the thickness of the phosphor layer 214 in the green (G) discharge cell may be substantially the same as or different from the thickness of the phosphor layer 214 in the blue (B) discharge cell.

Meanwhile, in the above description of FIG. 2A, only the case where the first electrode 202 and the second electrode 203 are formed of one layer each is illustrated and described. However, the first electrode 202 or the second electrode is different from the above description. It is also possible that one or more of 203 consists of a plurality of layers. This will be described with reference to FIG. 2B.

Referring to FIG. 2B, the first electrode 202 and the second electrode 203 may be formed of a plurality of layers, for example, two layers.

In particular, in consideration of light transmittance and electrical conductivity, the first electrode 202 and the second electrode 203 are substantially made of silver (Ag) in order to emit light generated in the discharge cell to the outside and to secure driving efficiency. It is preferable to include bus electrodes 202b and 203b including an opaque material and transparent electrodes 202a and 203a including a transparent material such as transparent indium tin oxide (ITO).

As such, the reason for the first electrode 202 and the second electrode 203 to include the transparent electrodes 202a and 203a is that the visible light generated in the discharge cell is effectively emitted when emitted to the outside of the plasma display panel. To make it possible.

In addition, the reason why the first electrode 202 and the second electrode 203 include the bus electrodes 202b and 203b is that the first electrode 202 and the second electrode 203 are the transparent electrodes 202a and 203a. ), The driving efficiency can be reduced because the electrical conductivity of the transparent electrodes 202a and 203a is relatively low, so that the lower of the transparent electrodes 202a and 203a can cause such a reduction in the driving efficiency. To compensate for electrical conductivity.

As described above, when the first electrode 202 and the second electrode 203 include the bus electrodes 202b and 203b, the transparent electrodes 202a, It is preferable that a black layer (220, 221) is further provided between the 203a and the bus electrodes 202b and 203b.

Meanwhile, the transparent electrodes 202a and 203a may be omitted in the same structure as in FIG. 2B. For example, the first electrode 202 and the second electrode 203 may be formed of only the bus electrodes 202b and 203b without the transparent electrodes 202a and 203a in FIG. 2B. That is, the first electrode 202 and the second electrode 203 are ITO-Less electrodes made of one layer of the bus electrodes 202b and 203b.

In the meantime, only one example of the plasma display panel included in the plasma display apparatus according to the exemplary embodiment of the present invention is illustrated and described, and the present invention is not limited to the plasma display panel having the above-described structure. For example, the description hereinabove illustrates only the case where the top dielectric layer at number 204 and the bottom dielectric layer at number 215 are each one layer, but one or more of these top dielectric layers and bottom dielectric layers are a plurality of layers. It can also be layered.

In addition, a black layer (not shown) may be further formed on the partition 212 to prevent reflection of external light due to the partition 212.

In addition, a black layer (not shown) may be further formed at a specific position on the front substrate 201 corresponding to the partition 212.

In addition, the width or thickness of the third electrode 213 formed on the rear substrate 211 may be substantially constant, but the width or thickness inside the discharge cell may be different from the width or thickness outside the discharge cell. will be. For example, the width or thickness inside the discharge cell may be wider or thicker than that outside the discharge cell.

As such, the structure of the plasma display panel according to the present invention may be variously changed.

Next, FIG. 3 is a diagram for describing a frame for implementing gray levels of an image in a plasma display device according to an embodiment of the present invention.

4 is a view for explaining an example of the operation of the plasma display device according to an embodiment of the present invention.

First, referring to FIG. 3, a frame for realizing gray levels of an image in a plasma display device according to an exemplary embodiment of the present invention is divided into several subfields having different emission counts.

Although not illustrated, one or more subfields among the plurality of subfields may be grayed out according to a reset period for initializing all discharge cells, an address period for selecting discharge cells to be discharged, and the number of discharges. It can be divided into the sustain period (Sustain Period) that implements.

For example, when the image is to be displayed in 256 gray scales, one frame is divided into eight subfields SF1 to SF8 as shown in FIG. 3, and each of the eight subfields SF1 to SF8 is represented. The reset period, the address period and the sustain period are further divided.

The gray scale weight of the corresponding subfield may be set by adjusting the number of the sustain signals supplied in the sustain period. That is, a predetermined gray scale weight can be given to each subfield using the sustain period. For example, the gray scale weight of each subfield is 2 ⁿ by setting the gray scale weight of the first subfield to 2 ⁰ and the gray scale weight of the second subfield to 2 ¹ (where n = 0, 1). , 2, 3, 4, 5, 6, and 7) to increase the gray scale weight of each subfield. As described above, the number of sustain signals supplied in the sustain period of each subfield is adjusted according to the gray scale weight in each subfield, thereby implementing gray levels of various images.

The plasma display apparatus according to an embodiment of the present invention uses a plurality of frames to implement an image, for example, to display an image of 1 second. For example, 60 frames are used to display an image of 1 second. In this case, the length of one frame may be 1/60 second, that is, 16.67 ms. The length of such a frame may vary.

In FIG. 3, only one frame is composed of eight subfields. However, the number of subfields forming one frame may be changed in various ways. For example, one frame may be configured with 12 subfields from the first subfield to the twelfth subfield, or one frame may be configured with 10 subfields.

Also, in FIG. 3, subfields are arranged according to the order of increasing the magnitude of gray scale weight in one frame. Alternatively, subfields may be arranged in the order of decreasing gray scale weight in one frame. Subfields may be arranged regardless of the weight.

Next, referring to FIG. 4, an example of an operation of the plasma display apparatus according to an exemplary embodiment of the present invention in any one of a plurality of subfields included in the same frame as in FIG. 3 is shown.

First, the first ramp-down signal may be supplied to the first electrode Y by the driver 110 of FIG. 1 in the pre-reset period before the reset period.

In addition, while the first falling ramp signal is supplied to the first electrode Y, a pre-sustain signal in a polarity opposite to the first falling ramp signal may be supplied to the second electrode Z.

Here, it is preferable that the first falling ramp signal supplied to the first electrode Y gradually descends to the tenth voltage V10.

In addition, it is preferable that the pre-sustain signal maintain the pre-sustain voltage Vpz substantially constant. Here, it is preferable that the pre-sustain voltage Vpz is approximately the same voltage as the voltage of the sustain signal SUS supplied in the subsequent sustain period, that is, the sustain voltage Vs.

As such, when the first falling ramp signal is supplied to the first electrode Y and the presuspension signal is supplied to the second electrode Z in the pre-reset period, a wall of a predetermined polarity is formed on the first electrode Y. Wall charges are accumulated, and wall charges of opposite polarity to the first electrode Y are accumulated on the second electrode Z. For example, positive wall charges are accumulated on the first electrode Y, and negative wall charges are accumulated on the second electrode Z.

This makes it possible to generate a set-up discharge of sufficient intensity in the subsequent reset period, which in turn makes it possible to perform the initialization sufficiently stably.

In addition, even when the voltage of the rising ramp signal Ramp-Up supplied to the first electrode Y becomes smaller in the reset period, it is possible to generate the setup discharge of sufficient intensity.

From the viewpoint of securing the driving time, the pre-reset period is included before the reset period in the subfield arranged in time among the subfields of the frame, or the pre-reset before the reset period in two or three subfields of the subfield of the frame. It is also possible to include a period.

Alternatively, this pre-reset period may be omitted in all subfields.

After the pre-reset period, in a set-up period of a reset period for initialization, a ramp-up signal in a direction opposite to that of the first falling ramp signal may be supplied to the first electrode Y.

Here, the rising ramp signal may include a first rising ramp signal gradually increasing with a first slope from the twentieth voltage V20 to the thirtieth voltage V30 and the second rising ramp signal from the thirtieth voltage V30 to the forty-th voltage V40. It may include a second rising ramp signal rising to the slope.

In this setup period, a weak dark discharge, that is, setup discharge, occurs in the discharge cell by the rising ramp signal. This setup discharge causes a certain amount of wall charges to accumulate in the discharge cell.

Here, it is preferable that the second slope of the second rising ramp signal is gentler than the first slope. As such, when the second slope is made gentler than the first slope, the voltage is increased relatively quickly until the setup discharge occurs, and the voltage is increased relatively slowly while the setup discharge occurs. The amount of light generated by the setup discharge can be reduced.

Accordingly, the contrast characteristic can be improved.

In a set-down period after the set-up period, a second ramp-down signal in a direction opposite to that of the ramp ramp signal may be supplied to the first electrode Y after the ramp ramp signal.

Here, it is preferable that the second falling ramp signal gradually decreases from the twentieth voltage V20 to the fifty voltage V50.

As a result, weak erase discharge, that is, set-down discharge, occurs in the discharge cell. By this set-down discharge, wall charges such that address discharge can be stably generated in the discharge cells remain uniformly.

5A to 5B are diagrams for describing another form of the rising ramp signal or the second falling ramp signal.

First, referring to FIG. 5A, the rising ramp signal gradually increases from the thirtieth voltage V30 to the forty-th voltage V40 after rapidly rising to the thirtieth voltage V30.

As such, the rising ramp signal may rise gradually with different inclinations over two stages, as shown in FIG. 4, and in various forms, such as gradually rising in one stage as shown here in FIG. 5A. It is possible to change.

Next, referring to FIG. 5B, the second falling ramp signal has a form in which the voltage gradually decreases from the thirtieth voltage V30.

As described above, the second falling ramp signal may be changed in various forms, such as a different point in time at which the voltage falls.

Meanwhile, in the address period after the reset period, a scan bias signal that substantially maintains a voltage higher than the 50 th voltage V50 of the second falling ramp signal may be supplied to the first electrode Y. FIG.

In addition, the scan signal Scan, which decreases from the scan bias signal by the scan voltage ΔVy, may be supplied to all of the first electrodes Y1 to Yn.

For example, the first scan signal Scan 1 is supplied to the first first electrode Y1 of the plurality of first electrodes Y, and then the second scan signal (2) is applied to the second first electrode Y2. Scan 2) is supplied, and the n th scan signal Scan n is supplied to the n th first electrode Yn.

On the other hand, the width of the scan signal in units of subfields may vary. That is, the width of the scan signal Scan in at least one subfield may be different from the width of the scan signal Scan in other subfields. For example, the width of the scan signal Scan in the subfield located later in time may be smaller than the width of the scan signal Scan in the subfield located earlier. In addition, the scan signal scan width decreases according to the arrangement order of the subfields gradually, such as 2.6 ms (microseconds), 2.3 ms (microseconds), 2.1 ms (microseconds), 1.9 ms (microseconds), and the like. Or 2.6 ㎲ (microseconds), 2.3 ㎲ (microseconds), 2.3 ㎲ (microseconds), 2.1 ㎲ (microseconds) ... 1.9 ㎲ (microseconds), 1.9 ㎲ (microseconds) It could be done.

As such, when the scan signal Scan is supplied to the first electrode Y, a data signal rising by the magnitude ΔVd of the data voltage may be supplied to the third electrode X to correspond to the scan signal.

As the scan signal Scan and the data signal Data are supplied, the voltage difference between the voltage of the scan signal and the data voltage Vd of the data signal and the wall voltage due to the wall charges generated in the reset period. In addition, address discharge is generated in the discharge cells to which the voltage Vd of the data signal is supplied.

Here, it is preferable that the sustain bias signal is supplied to the second electrode Z in order to prevent the address discharge from becoming unstable due to the interference of the second electrode Z in the address period.

Here, it is preferable that the sustain bias signal maintain a substantially constant sustain bias voltage Vz smaller than the voltage of the sustain signal supplied in the sustain period and larger than the voltage of the ground level GND.

Thereafter, the sustain signal SUS may be alternately supplied to the first electrode Y and / or the second electrode Z in the sustain period for displaying an image. The sustain signal SUS preferably has a magnitude of a voltage of ΔVs.

When the sustain signal SUS is supplied, the discharge cell selected by the address discharge is added to the first electrode when the wall voltage in the discharge cell and the sustain voltage Vs of the sustain signal SUS are added and the sustain signal SUS is supplied. A sustain discharge, that is, a display discharge, occurs between (Y) and the second electrode Z.

6 is a diagram for explaining another type of the sustain signal.

Referring to FIG. 6, a positive sustain signal and a negative sustain signal are alternately supplied to one of the first electrodes Y and the second electrode Z, for example, the first electrode. do.

As described above, it is preferable that the bias signal is supplied to the other electrode, for example, the second electrode Z, while the positive sustain signal and the negative sustain signal are supplied to any one electrode.

Here, the bias signal preferably maintains the voltage at the ground level GND substantially constant.

As shown in FIG. 6, when the sustain signal is supplied only to one of the first electrode Y and the second electrode Z, one of the first electrode Y and the second electrode Z may be used. Only one driving board in which circuits for supplying a sustain signal is arranged is required.

As a result, the overall size of the driving unit can be reduced, thereby reducing the manufacturing cost.

Next, FIG. 7 is a diagram for explaining a specific mode.

Referring to FIG. 7, when a specific image is displayed on the plasma display panel, the display may be set to a specific mode when the threshold image is displayed for more than a threshold time.

For example, when a specific image starts to be displayed on the plasma display panel from time t0 and continues to be displayed until time t1, the specific mode may be entered at time t1.

Here, the specific mode is preferably a mode in which an image having substantially the same average power level (APL) is displayed for a threshold time or more. Here, the threshold time may be determined within a range of 10 seconds to 30 minutes.

This average power level will be described in more detail with reference to FIG. 9.

The driving unit of the plasma display device according to an embodiment of the present invention reduces the number of sustain signals per unit gray level supplied to at least one of the first electrode and the second electrode of the plasma display panel in this particular mode.

For example, at the initial time t1 when entering a specific mode, the number of sustain signals per unit gradation is a, and when the time Δt has passed after entering the specific mode, that is, the number of sustain signals per unit gradation at the time t1 + Δt Is b less than a.

As such, the reason for reducing the number of sustain signals per unit gray level in a specific mode will be described with reference to FIG. 8.

FIG. 8 is a diagram for explaining a reason for reducing the number of sustain signals per unit gray level in a specific mode.

Referring to FIG. 8, it is assumed that an image of a window pattern is locally displayed for a predetermined time or more on a screen of a plasma display panel as shown in (a).

As described above, when the image of the window pattern is continuously displayed for more than a predetermined time, even if the image of the window pattern is turned off, the window is displayed at the position where the image of the window pattern was displayed on the screen of the plasma display panel as shown in (b). Afterimages similar to patterns remain faint.

That is, even after the image is switched, afterimages in which a part of the previously displayed image remain dim on the screen occur.

This afterimage occurs because a distribution of wall charges in a discharge cell is fixed in accordance with the pattern of the specific image when a specific image is continuously displayed on the screen for a predetermined time or more.

In order to prevent such an afterimage, the number of sustain signals per unit gray level is reduced when a specific image, preferably an image having substantially the same average power level, is displayed on the plasma display panel for more than a threshold time.

Then, the intensity of the sustain discharge occurring in the discharge cell is reduced, and accordingly, the occurrence of the afterimage can be reduced by shaking the distribution of the fixed wall charges.

Next, FIG. 9 is a diagram for explaining an average power level.

Referring to FIG. 9, the average power level is a method of adjusting the number of sustain signals in relation to the size of a portion where an image is displayed on the plasma display panel. That is, the average power level is determined according to the number of discharge cells that are turned on among the discharge cells of the plasma display panel.

Preferably, as the value of the average power level APL increases, the number of sustain signals per unit gray scale decreases, and as the value of the average power level APL decreases, the number of sustain signals per unit gray scale increases.

For example, when an image is displayed on a portion of a relatively small area on the screen of the plasma display panel 900 as shown in (a), that is, the number of discharge cells that are turned on among the discharge cells formed in the plasma display panel is In a relatively small case (in this case, the APL level is relatively low), since the number of discharge cells contributing to the image display is relatively small, the number of sustain signals per unit gradation supplied to each discharge cell contributing to the image display. To be relatively large. Accordingly, the overall brightness of the image can be increased.

On the contrary, when the image is displayed on a relatively large area on the screen of the plasma display panel 900 as shown in (b), that is, when the number of discharge cells turned on among the discharge cells formed on the plasma display panel is relatively large. (In this case, the APL level is relatively high.) Since the number of discharge cells contributing to the image display is relatively large, the number of sustain signals per unit gradation supplied to each discharge cell contributing to the image display is relatively small. do. This prevents a sudden increase in the total power consumption of the plasma display panel.

As an example, when the average power level is a level, in this case, the number of sustain signals per unit gradation is N.

In addition, when the average power level is a b level higher than the above-described a level, the number of sustain signals per unit gray level may be M less than N described above.

Next, FIG. 10 is a diagram for describing an example of a method of reducing the number of sustain signals per unit gray level in relation to an average power level.

11 is a view for explaining another example of a method of reducing the number of sustain signals per unit gray level in relation to the average power level.

First, referring to FIG. 10, when the average power level is different, the amount of decrease in the number of sustain signals as the duration of a specific mode increases in a specific mode is different.

Here, ① is a case where the average power level is relatively low. It is assumed that this case of 1 is the first level. In addition, in the case of ②, the average power level is higher than in the case of ①. Assume that the case of ② is the second level. In addition, in the case of ③, the average power level is higher than in the case of ②. Suppose that 3 is the third level.

In this case, in the case of? Where the average power level is the first level in a specific mode, it is assumed that the number of sustain signals per unit gray level reduced is the first number. Here, in the case of ②, the number of sustain signals per unit gray level reduced is less than the first number, and in the case of ③, the number of the sustain signals per unit gray level reduced is less than the first number and the second number. 3 count.

For example, in the case of ①, the number of sustain signals per unit gradation is 100 in normal mode, and in case of ②, the number of sustain signals per unit gradation is 60 in normal mode, and in case of ③, per unit gradation in normal mode. Assume that the number of sustain signals is 40.

Herein, when the image having substantially the same average power level is displayed on the plasma display panel for more than the threshold time and enters a specific mode and the time t1 has passed, in the case of ①, the number of sustain signals per unit gray scale is 50. That is, the number of sustain signals per unit gradation to be reduced (the first number) is 50, and in the case of ②, the number of the sustain signals per unit gradation is less than 40, i.e., the sustain signals per unit gradation to be reduced. In the case of (3), the number (2nd number) may be 30, and the number of sustain signals per unit gradation is 30, that is, the number of sustain signals per unit gradation (third number) is 10.

In other words, in the case where the average power level is relatively low in a particular mode, the number of sustain signals that decrease as the specific mode duration increases is larger than in the case where the average power level is relatively high.

As such, when the average power level is a relatively low level, the number of sustain signals per unit gradation that decreases according to a specific mode duration is relatively high. When the average power level is relatively low, the sustain per unit gradation is relatively low. Due to the relatively large number of signals, the distribution of wall charges in a particular mode may be more fixed than when the average power level is relatively high.

Therefore, when the average power level is a relatively low level, the number of sustain signals per unit gradation that decreases according to a specific mode duration in a particular mode is made relatively higher, so that afterimages are adaptively generated according to the change of the average power level. It can be reduced.

Next, referring to FIG. 11, the total level of average power level is divided into three or more groups, for example, five groups as shown here in FIG. 11, and in this case, the sustain signal per unit gray level decreases in a specific mode. The number can be different for each group.

For example, assuming that the average power level is divided into a total of 1024 levels, the lower 20% level of the average power level in a specific mode reduces the number of sustain pulses per unit gray level according to the first type (①), 20% to 40% reduces the number of sustain pulses per unit gradation according to the second type (②), and 40% to 60% reduces the number of sustain pulses per unit gradation according to the third type (③), From 60% to 80%, the number of sustain pulses per unit gradation can be reduced according to the fourth type (④), and from 80% to 100%, the number of sustain pulses per unit gradation can be reduced according to the fifth type (⑤). have.

In addition, the number of sustain signals per unit gray level decreases in the order of the first type, the second type, the third type, and the fourth type.

In the fifth type, even in a specific mode, the number of sustain signals per unit gray level can be maintained without decreasing. That is, at some higher levels of the average power level, the number of sustain signals per unit gray level is kept constant even in a specific mode.

More preferably, the number of sustain pulses per unit gray level in a certain mode is kept constant at a level within the upper 10% of the total average power level.

The reason for this setting is that since the area where the image is displayed is relatively large at the upper level, if the number of sustain pulses per unit gradation is reduced, the luminance reduction value of the image felt by the human eye is relatively large, which may deteriorate the image quality. Because of this.

As such, the technical configuration of the present invention described above can be understood by those skilled in the art that the present invention can be implemented in other specific forms without changing the technical spirit or essential features of the present invention.

Therefore, the exemplary embodiments described above are to be understood as illustrative and not restrictive in all respects, and the scope of the present invention is indicated by the appended claims rather than the foregoing detailed description, and the meaning and scope of the claims are as follows. And all changes or modifications derived from the equivalent concept should be interpreted as being included in the scope of the present invention.

As described in detail above, the plasma display apparatus of the present invention has an effect of adaptively reducing the occurrence of afterimages by controlling the number of sustain signals per unit gray level which are reduced in relation to the average power level.

Claims (4)

A plasma display panel including a first electrode and a second electrode parallel to each other; Per unit gradation supplied to at least one of the first electrode and the second electrode in a sustain period for displaying an image, and supplied to at least one of the first electrode and the second electrode in a specific mode. The number of sustain signals per unit gradation at a second level different from the first level is reduced by reducing the number of sustain signals, and the average power level being the number of decreases of the sustain signal per unit gradation at a first level. Driving part different from Plasma display device comprising a. The method of claim 1, The first level is lower than the second level, And the number of decreases of the sustain signal per unit gray level in the first level is greater than the number of decreases of the sustain signal per unit gray level in the second level. The method of claim 1, And the specific mode is a mode in which an image having substantially the same average power level is displayed over a threshold time. The method of claim 3, wherein And the threshold time is determined within a range of 30 seconds to 10 minutes.

Images